Question

我有一个数据：

dt <- fread("id date    Note    Amount
  A 2/15/2012   Keep this   10
  A 5/9/2012    Keep this   30
  A 5/15/2012   Keep this   50
  A 8/26/2012   Keep this   10
  A 11/2/2012   Keep this   10
  B 4/3/2012    Keep this   5
  B 7/3/2012    Keep this   5
  ", header = T)
   id      date      Note Amount
1:  A 2/15/2012 Keep this     10
2:  A  5/9/2012 Keep this     30
3:  A 5/15/2012 Keep this     50
4:  A 8/26/2012 Keep this     10
5:  A 11/2/2012 Keep this     10
6:  B  4/3/2012 Keep this      5
7:  B  7/3/2012 Keep this      5

我想要的是：

fread("id   YrMonth Amount  Note
A   2012-01 0   Keep this
A   2012-02 10  Keep this
A   2012-03 0   Keep this
A   2012-04 0   Keep this
A   2012-05 80  Keep this
A   2012-06 0   Keep this
A   2012-07 0   Keep this
A   2012-08 10  Keep this
A   2012-09 0   Keep this
A   2012-10 0   Keep this
A   2012-11 10  Keep this
A   2012-12 0   Keep this
B   2012-01 0   Keep this
B   2012-02 0   Keep this
B   2012-03 0   Keep this
B   2012-04 5   Keep this
B   2012-05 0   Keep this
B   2012-06 0   Keep this
B   2012-07 5   Keep this
B   2012-08 0   Keep this
B   2012-09 0   Keep this
B   2012-10 0   Keep this
B   2012-11 0   Keep this
B   2012-12 0   Keep this
", header = T)

首先，我尝试如下代码：

library(data.table)
dt[, YrMonth := ymd(paste(format(date, "%Y-%m"), 01, sep = "-"))]

但是，我不知道如何创建原始数据不包括的日期。我认为我可以先分组的想法。使用dcast将数据从长到宽转换并设置参数fill = 0。之后，我可以通过melt将其切换回去。
有更好的方法可以快速找出答案吗？
谢谢。

分组数据并创建日期列

0 个答案: